Fix two small silent rules omissions
Silence warnings about unused return values in ic

The warnings are:

oe_ei_encode_string.c:26:3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_string(0,&size,p);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~

oe_ei_encode_port.c:26:3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_port(NULL, &size, p);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

oe_ei_encode_atom.c:26:3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_atom(0,&size,p);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~

oe_ei_encode_pid.c:26::3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_pid(NULL, &size, p);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

oe_ei_encode_ref.c:26:3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_ref(NULL, &size, p);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

oe_ei_encode_term.c:26:3: warning: expression result unused [-Wunused-value]
  (int) ei_encode_term(NULL, &size, t);
  ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Prepare release